1. Field of the Invention
Embodiments of the present invention generally relate to an apparatus and a method for processing semiconductor substrates. More particularly, embodiments of the present invention provide apparatus and method for polishing semiconductor substrates.
2. Description of the Related Art
Sub-micron multi-level metallization is one of the key technologies for the next generation of ultra large-scale integration (ULSI). The multilevel interconnects that lie at the heart of this technology require planarization of interconnect features formed in high aspect ratio apertures, including contacts, vias, trenches and other features. Reliable formation of these interconnect features is very important to the success of ULSI and to the continued effort to increase circuit density and quality on individual substrates and die.
In the fabrication of integrated circuits and other electronic devices, multiple layers of conductive, semi-conductive, and dielectric materials are deposited on or removed from a surface of a substrate. Thin layers of conductive, semiconductive, and dielectric materials may be deposited by a number of deposition techniques. As layers of materials are sequentially deposited and removed, the uppermost surface of the substrate may become non-planar across its surface and require planarization.
Planarization is generally performed using Chemical Mechanical Polishing (CMP) and/or Electro-Chemical Mechanical Deposition (ECMP). A planarization method typically requires that the substrate be mounted in a wafer head, with the surface of the substrate to be polished exposed. The substrate supported by the head is then placed against a rotating polishing pad. The head holding the substrate may also rotate, to provide additional motion between the substrate and the polishing pad surface. Further, a polishing slurry (typically including an abrasive and at least one chemically reactive agent therein, which are selected to enhance the polishing of the topmost film layer of the substrate) is supplied to the pad to provide an abrasive chemical solution at the interface between the pad and the substrate. The combination of polishing pad characteristics, the specific slurry mixture, and other polishing parameters can provide specific polishing characteristics.
Polishing is generally performed in multiple steps at three or less polishing stations, each having specific polishing characteristics, to achieve desired results. Therefore, a polishing system generally has two or three polishing stations each configured to perform a specific polishing step. Conventional polishing systems generally have one mainframe on which the two or three polishing stations and at least one load cup are disposed. Conventional polishing systems also have multiple polishing heads movably positioned on the mainframe. The conventional polishing systems have limited flexibility in polishing station configuration to meet different process requirements or to adapt changes.
Therefore, there is a need for a polishing apparatus which provides flexibility in system configuration to meet various process requirements.